With the growth of the print-on-demand markets in the recent years, the demands in high reliability for electrophotographic techniques are even more increasing. Especially, it has been earnestly desired that toners usable in electrophotographic methods have even more improved properties in durability, heat-resistant storage property, and high-temperature offset resistance, and the like.
On the other hand, in toners, which are developers for electrophotographic methods, use of a polylactic acid, which is a plant-derived raw material, has been studied, for the purpose of reducing environmental loads.
For example, for the purpose of obtaining a toner having excellent low-temperature fusing ability and gloss, disclosed is a method for producing a toner, including a molten mixing step including mixing a lignin-based compound and a polylactic acid in a molten state, thereby causing a transesterification reaction between the lignin-based compound and the polylactic acid, to provide a reaction product as a resin binder (see Patent Publication 1).
In addition, disclosed is a toner for electrophotography prepared by subjecting a raw material mixture containing a resin binder comprising a polylactic acid and a colorant to a kneading treatment for a plural times having reduced environmental loads during the production and the waste treatment (see Patent Publication 2).
Further, disclosed is a toner for electrophotography characterized by the use of a resin containing a degradable polyester resin comprising a poly α-hydroxycarboxylic acid and a polyester-based resin other than the above that shows excellent deinking property and a degree of whiteness, and has excellent wax dispersibility, fusing ability, pulverizability, hot offset resistance, and storage property, thereby showing excellent properties as a toner for electrophotography (see Patent Publications 3 and 4).